Results of Scoping Studies for Determining Radiolytic Hydrogen Production from Moist CST and CST Slurries

In support of the Salt Disposition team, scoping studies have been performed on the radiolysis of moist and aqueous slurries of Crystalline Silicotitanate(CST). If CST is used for removal of Cs-137 from SRS salt solutions, radiolysis of the water by Cs-137 on the CST will produce H2. Also it has been shown that the presence of a solid in the system can enhance the production of H2 by transferring absorbed energy from the solid to the water (1). As indicated in the test plan (2) for this scoping study, it is the intent of this study to determine if CST enhances the radiolytic production of H2 and to estimate the radiolytic hydrogen generation rate from an aqueous CST slurry in a column at the maximum expected Cs-137 loading on the CST.Initially several CST slurry systems were irradiated with Co-60 gamma rays and the radiolytic yield of H2 measured in terms of its G value (molecules of H2 produced per 100 eV of energy absorbed). Based on the results of these tests it was determined that CST did not enhance the radiolytic production of H2 by transferring energy to the water and causing it to decompose.Calculations were then performed to estimate the rate of H2 production from a process column 16ft. long by 5ft. in diameter containing CST that was fully loaded with Cs-137. The maximum rate of H2 production based on the G values measured in this study was one liter per minute at STP (0.04 cfm). This was for a 63 percent water/CST slurry with a G value of 0.2 molecules/100eV for H2 production and a loading of 1 gram of Cs-137 per 100 grams of resin. The present work also indicates that for a column containing salt solution and CST rather than water and CST, the rate would be 4X lower. This lower value is much more realistic